There is a continuous demand, particularly in the food and beverage industry, for articles, such as bottles, buckets, pitchers, funnels, etc., made of clear, tough plastic because they are relatively inexpensive, easy to use, generally non-breakable and serve as a good substitute for glass. It is often-times desirable that such articles have handles thereon to aid in their use, particularly when of large size. U.S. Pat. No. 4,713,207 discloses a method of making a plastic container with an integral handle member thereon. The method disclosed includes the step of extruding a thermoplastic parison between sections of a mold and then blowing the container. Since it is generally understood that PET does not have sufficient hot melt strength to be extrusion blow molded, however, other thermoplastic materials, such as high density polyethylene and polyvinyl chloride, must be used to produce blow molded containers where the handle is integral with the container.
When PET is used and handles are desired, it has been the practice to attach the handle to the PET article in a separate operation, such as by ultrasonic fusion, after the blow molded PET article has been formed in and removed from the blow mold. U.S. Pat. No. 4,727,997 discloses a method and apparatus for producing a PET bottle with a PET handle. In a first step, a parison is blow molded in a blow mold which has inwardly extending circumferential ridges to produce a blown bottle with article-encircling grooves therein. In a second step, the blow molded bottle is transferred to a second mold, a grip molding mold, which has circumferential grooves therein, and a handle is injection molded and attached to the bottle by way of circumferential connecting rings seated in the circumferential grooves in the bottle.
Another approach has been to injection mold a thermoplastic handle in an operation separate and apart from the blow molding of the container, and snap the separately molded handle over the neck or finish of the blown PET bottle. In accordance with a still further proposal, the separately molded handle is inserted in the blow mold and the bottle is blown over/into the handle.
Still another approach is disclosed in the German No. 3,443,715 and Japanese No. 52-33662 references. The schemes disclosed therein are directed to apparatus including an injection mold cavity that communicates with a blow mold cavity, and movable injection mold-defining members that move within the blow mold. The movable injection mold-defining members cover the portion of the injection mold that communicates with the blow mold while the projections are injection molded. Subsequently, the movable members are retracted or removed from the blow mold and the hollow article is blow molded against the previously-formed injection molded projection.
A further known scheme is described in the Japanese No. 60-147319 reference. This approach, which is not actually directed to forming an injection molded handle on a blow molded article, discloses injecting molten material into the corners of a blow mold cavity to fill in the corners of a blow molded article. The apparatus has a single mold cavity--a blow mold cavity.
None of the above practices, however, has been entirely satisfactory since they add steps to the fabrication process, utilize complicated molds with moving parts therein, may require ultrasonic bonding equipment or multiple separate molds, and are otherwise unduly time-consuming and expensive.